Inaccessible or confined areas such as, for example, the interior parts of gas turbine engines, often require routine inspection to verify the integrity of internal engine parts and maintain safe operation of the engine by identifying potential problems, i.e., defects in a part, prior to failure of the part, or to identify the source of an existing problem. For example, problems may be identified through visual inspection by use of a borescope, such as during routine downtime maintenance of the gas turbine engine.
Additional monitoring of the turbine engine may be performed during operation of the engine to further identify the condition of components located within the hot gas path of the engine. While a variety of structures and materials may be incorporated into a borescope used for inspection of the interior turbine components during downtime of the turbine engine when the components are relatively cool, visual monitoring of the turbine components during operation of the turbine provides additional restrictions on the monitoring equipment. In a known high temperature monitoring system, a viewing tube may be used to support optical components, i.e., a series of lenses, for conveying images obtained from a location in the hot gas path to a location at the exterior of the engine, and to isolate the optical components from the heat of the hot gases. In addition, a cooling air flow may be required, such as may be provided through a conduit from a cooling air source outside of the turbine engine for introducing a pressurized flow of a cooling fluid into the monitoring system.
Further, the available monitoring locations available for prior monitoring systems, such as those used for continuously monitoring turbine engine components during operation of the engine, have generally included those which provide a predetermined access path, such as a generally straight through access path, from an outer casing wall to an interior portion of the turbine engine. Accordingly, monitoring of components in turbine engines by continuous monitoring systems has generally been restricted to those locations that present substantially unobstructed access between the outer casing wall and the interior portion of the engine.